Don't look now, but the AI market just shifted -- and Advanced Micro Devices (AMD6.37%) investors are nervous.

Bloomberg reports Meta (META+3.35%) may purchase Tensor Processing Units (TPUs) designed by Alphabet (GOOG+1.18%) (GOOGL+1.05%) for use in Meta's artificial intelligence data centers. This is mainly bad news for Nvidia (NVDA3.48%) stock, because Nvidia has been selling a lot of Graphics Processing Units (GPUs) to Meta. It's also probably bad news for AMD, and AMD stock is now down 7.9% through 11:10 a.m. ET.